How to Gap Spark Plugs and Points

Spark plugs that have an incorrect gap setting can cause engine problems.

Often tyou can purchase spark plugs already gapped according to your engine's specifications. The gap setting is the distance the electricity is allowed to arc between the center and ground electrode at the tip of the spark plug. A spark plug that is not gapped correctly can cause the engine to function improperly. If you need to gap the spark plugs yourself, you can do so by obtaining the right gapping tool. To find out the correct gap setting, check the emissions tag under the hood of the vehicle, or check the owner's manual.

Things You'll Need

• Gap tool
• Spark plugs

Instructions

1. Obtain a gap tool. Coin-style gap tools are traditionally used, but NGK doesn't recommend the use of this tool with new precious-metal spark plugs. NGK recommends the use of a wire-style gap tool.

2. Check the current gap setting of the spark plug. To find out the current setting, insert the wire loops on the gap tool between the ground and center electrodes at the tip of the spark plug until you find a loop that fits snuggly in place. For example, if the gap setting should be 0.040 inch for that particular engine, the corresponding wire loop should fit snuggly. If it doesn't, you will need to adjust the gap.

3. Adjust the gap as needed. To adjust, use the flat surface provided on the gap tool to widen or narrow the gap between the electrodes. To widen the gap, insert the flat surface in between the electrodes and push up. To narrow the gap, place the flat surface on top of the ground electrode and push down.

4. Check the gap on the spark plug again by using the gap tool. Repeat the process of widening or narrowing as needed until the gap between the electrodes is at the proper setting.

References

• NGK Spark Plugs: Spark Plug Gap